1. Field of the Invention
This invention relates to fluorescent phosphor materials. More particularly, it is concerned with non-stoichiometric modified strontium orthophosphate phosphors coactivated with cerium and manganese.
2. Discussion of the Prior Art
Fluorescent phosphor materials employing a matrix of calcium or strontium orthophosphate have been the subject of some study.
For example, Kroger in Physica, 15:801 (1949) discusses the fluorescence of unmodified calcium or strontium orthophosphate phosphors coactivated with tin and manganese or with cerium and manganese.
Butler in J. Electrochem. Soc., 100:250 (1953) describes alkaline earth orthophosphate phosphors activated with tin or with tin and manganese. The tin-manganese coactivated phosphors disclosed by Butler employ a calcium orthophosphate host matrix modified by the incorporation of some strontium.
Koelmans et al. in J. Electrochem. Soc., 104:442 (1957) discuss tin activated strontium orthophosphate phosphors modified by the incorporation of aluminum, cadmium, calcium, magnesium, or zinc.
Sarver et al. in J. Electrochem. Soc., 108:1103 (1961) discuss phase equilibrium relationships and luminescence of tin activated strontium orthophosphate phosphors modified with calcium, magnesium, or zinc.